Compact Multi-Band PIFAs on a Semi-Populated Mobile Handset With Tunable Isolation

In this communication, miniaturized tunable two-antenna systems composed of printed inverted-F antennas (PIFAs) are developed for a semi-populated mobile phone handset. The PIFAs are loaded with a series combination of an inductor and a varactor to simultaneously achieve miniaturization and tunability. The compact 32 mm-long PIFAs demonstrate tuning range of more than 240 MHz covering personal telecommunication bands from LTE-band13 to GSM900 MHz. As well a miniaturized tunable parasitic element is integrated in the handset to efficiently suppress coupling between the PIFAs to below
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28 dB across the entire operational bandwidth of the antennas. Simulation and measurement results demonstrate the successful implementation of a tunable MIMO system with passive adjustable coupling reduction mechanism for mobile handsets and achievement of a channel capacity profile close to that of an un-correlated system.